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''Betula papyrifera'' (paper birch, also known as (American) white birch and canoe birch) is a short-lived species of
birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech- oak family Fagaceae. The genus ''Betula'' cont ...
native to northern
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and th ...
. Paper birch is named for the tree's thin white bark, which often peels in
paper Paper is a thin sheet material produced by mechanically or chemically processing cellulose fibres derived from wood, rags, grasses or other vegetable sources in water, draining the water through fine mesh leaving the fibre evenly distribu ...
like layers from the trunk. Paper birch is often one of the first species to colonize a burned area within the northern latitudes, and is an important species for
moose The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult ma ...
browsing. The wood is often used for
pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gene ...
and firewood.


Description

It is a medium-sized
deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, ...
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that are ...
typically reaching tall, and exceptionally to with a trunk up to in diameter. Within forests, it often grows with a single trunk but when grown as a landscape tree it may develop multiple trunks or branch close to the ground. Paper birch is a typically short-lived species. It handles heat and humidity poorly and may live only 30 years in zones six and up, while trees in colder-climate regions can grow for more than 100 years. ''B. papyrifera'' will grow in many soil types, from steep rocky outcrops to flat
muskeg Muskeg (Ojibwe: mashkiig; cr, maskīk; french: fondrière de mousse, lit. ''moss bog'') is a peat-forming ecosystem found in several northern climates, most commonly in Arctic and boreal areas. Muskeg is approximately synonymous with bog or p ...
s of the boreal forest. Best growth occurs in deeper, well drained to dry soils, depending on the location. * In older trees, the
bark Bark may refer to: * Bark (botany), an outer layer of a woody plant such as a tree or stick * Bark (sound), a vocalization of some animals (which is commonly the dog) Places * Bark, Germany * Bark, Warmian-Masurian Voivodeship, Poland Arts, e ...
is white, commonly brightly so, flaking in fine horizontal strips to reveal a pinkish or salmon-colored inner bark. It often has small black marks and scars. In individuals younger than five years, the bark appears a brown red color with white
lenticel A lenticel is a porous tissue consisting of cells with large intercellular spaces in the periderm of the secondarily thickened organs and the bark of woody stems and roots of dicotyledonous flowering plants. It functions as a pore, providing a ...
s, making the tree much harder to distinguish from other birches. The bark is highly weather-resistant. It has a high oil content and this gives it its waterproof and weather-resistant characteristics. Often, the wood of a downed paper birch will rot away, leaving the hollow bark intact. * The
leaves A leaf ( : leaves) is any of the principal appendages of a vascular plant stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, st ...
are dark green and smooth on the upper surface; the lower surface is often pubescent on the veins. They are alternately arranged on the stem, oval to triangular in shape, long and about two-thirds as wide. The leaf is rounded at the base and tapering to an acutely pointed tip. The leaves have a doubly serrated
margin Margin may refer to: Physical or graphical edges * Margin (typography), the white space that surrounds the content of a page *Continental margin, the zone of the ocean floor that separates the thin oceanic crust from thick continental crust *Leaf ...
with relatively sharp teeth. Each leaf has a petiole about long that connects it to the stems. * The fall color is a bright yellow color that contributes to the bright colors within the northern
deciduous forest In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals ...
. * The leaf buds are conical and small and green-colored with brown edges. * The stems are a reddish-brown color and may be somewhat hairy when young. * The
flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechanis ...
s are wind-pollinated
catkin A catkin or ament is a slim, cylindrical flower cluster (a spike), with inconspicuous or no petals, usually wind-pollinated (anemophilous) but sometimes insect-pollinated (as in '' Salix''). They contain many, usually unisexual flowers, arrang ...
s; the female flowers are greenish and long growing from the tips of twigs. The male ( staminate) flowers are long and a brownish color. The tree flowers from mid-April to June depending on location. Paper birch is
monoecious Monoecy (; adj. monoecious ) is a sexual system in seed plants where separate male and female cones or flowers are present on the same plant. It is a monomorphic sexual system alongside gynomonoecy, andromonoecy and trimonoecy. Monoecy is ...
, meaning that one plant has both male and female flowers. * The
fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in partic ...
matures in the fall. The mature fruit is composed of numerous tiny winged
seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosper ...
s packed between the catkin bracts. They drop between September and spring. At 15 years of age, the tree will start producing seeds but will be in peak seed production between 40 and 70 years. The seed production is irregular, with a heavy seed crop produced typically every other year and with at least some seeds being produced every year. In average seed years, are produced, but in bumper years may be produced. The seeds are light and blow in the wind to new areas; they also may blow along the surface of snow. * The roots are generally shallow and occupy the upper of the soil and do not form taproots. High winds are more likely to break the trunk than to uproot the tree.


Genetics and taxonomy

''B. papyrifera'' hybridizes with other species within the genus ''Betula''. Several varieties are recognized: * ''B. p.'' var ''papyrifera'' the typical paper birch * ''B. p.'' var ''cordifolia'' the eastern paper birch (now a separate species); see Betula cordifolia * ''B. p.'' var ''kenaica'' Alaskan paper birch (also treated as a separate species by some authors); see Betula kenaica * ''B. p.'' var ''subcordata'' Northwestern paper birch * ''B. p''. var. ''neoalaskana'' Alaska paper birch (although this is often treated as a separate species); see Betula neoalaskana


Distribution

''Betula papyrifera'' is mostly confined to Canada and the far northern United States. It is found in interior (var. ''humilus'') and south-central (var. ''kenaica'')
Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U ...
and in all
provinces and territories of Canada Within the geographical areas of Canada, the ten provinces and three territories are sub-national administrative divisions under the jurisdiction of the Constitution of Canada, Canadian Constitution. In the 1867 Canadian Confederation, three pr ...
, except
Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the '' Nunavut Act'' and the '' Nunavut Land Claims Agreement Act'' ...
, as well as the far northern continental
United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country Continental United States, primarily located in North America. It consists of 50 U.S. state, states, a Washington, D.C., ...
. Isolated patches are found as far south as the Hudson Valley of
New York New York most commonly refers to: * New York City, the most populous city in the United States, located in the state of New York * New York (state), a state in the northeastern United States New York may also refer to: Film and television * '' ...
and
Pennsylvania Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
, northern
Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the ...
, and
Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...
. High elevation stands are also in mountains to
North Carolina North Carolina () is a U.S. state, state in the Southeastern United States, Southeastern region of the United States. The state is the List of U.S. states and territories by area, 28th largest and List of states and territories of the United ...
,
New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe, New Mexico, Santa Fe , LargestCity = Albuquerque, New Mexico, Albuquerque , LargestMetro = Albuquerque metropolitan area, Tiguex , Offi ...
, and
Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of the ...
. The most southerly stand in the Western United States is located in Long Canyon in the City of Boulder Open Space and Mountain Parks. This is an isolated Pleistocene relict that most likely reflects the southern reach of boreal vegetation into the area during the last Ice Age.


Ecology

In Alaska, paper birch often naturally grows in pure stands by itself or with
black Black is a color which results from the absence or complete absorption of visible light. It is an achromatic color, without hue, like white and grey. It is often used symbolically or figuratively to represent darkness. Black and white ha ...
or
white spruce White spruce is a common name for several species of spruce (''Picea'') and may refer to: * ''Picea glauca'', native to most of Canada and Alaska with limited populations in the northeastern United States * ''Picea engelmannii ''Picea engelman ...
. In the eastern and central regions of its range, it is often associated with red spruce and
balsam fir ''Abies balsamea'' or balsam fir is a North American fir, native to most of eastern and central Canada (Newfoundland west to central Alberta) and the northeastern United States (Minnesota east to Maine, and south in the Appalachian Mountains to ...
. It may also be associated with big-toothed aspen,
yellow birch ''Betula alleghaniensis'', the yellow birch, golden birch, or swamp birch, is a large tree and an important lumber species of birch native to northeastern North America. Its vernacular names refer to the golden color of the tree's bark. In the pa ...
, ''
Betula populifolia ''Betula populifolia'' (gray or grey birch) is a deciduous tree native to eastern North America. Range It ranges from southeastern Ontario east to Nova Scotia, and south to Pennsylvania and New Jersey, with disjunct populations in Indiana, Vir ...
'', and maples. Shrubs often associated with paper birch in the eastern part of its range include beaked hazel (''
Corylus cornuta ''Corylus cornuta'', the beaked hazelnut (or just ''beaked hazel''), is a deciduous shrubby hazel with two subspecies found throughout most of North America. Description The beaked hazelnut can reach tall with stems thick with smooth gray b ...
''), common bearberry ('' Arctostaphylos uva-ursi''), dwarf bush-honeysuckle (''
Diervilla lonicera ''Diervilla lonicera'', commonly referred to as northern bush honeysuckle, low bush honeysuckle, dwarf bush honeysuckle, or yellow-flowered upright honeysuckle, is a deciduous shrub native to the northeastern United States and Canada. Its specifi ...
''), wintergreen ('' Gaultheria procumbens''), wild sarsaparilla (''
Aralia nudicaulis ''Aralia nudicaulis'' (commonly wild sarsaparilla,Dickinson, T.; Metsger, G.; Hull, J.; and Dickinson, R. (2004) The ROM Field Guide to Wildflowers of Ontario. Toronto:Royal Ontario Museum, p. 140. false sarsaparilla, shot bush, small spikenard, ...
''), blueberries ('' Vaccinium spp.''), raspberries and blackberries (''
Rubus ''Rubus'' is a large and diverse genus of flowering plants in the rose family, Rosaceae, subfamily Rosoideae, with over 1,350 species. Raspberries, blackberries, and dewberries are common, widely distributed members of the genus. Most of the ...
spp.''), elderberry (''
Sambucus ''Sambucus'' is a genus of flowering plants in the family Adoxaceae. The various species are commonly called elder or elderberry. The genus was formerly placed in the honeysuckle family, Caprifoliaceae, but was reclassified as Adoxaceae due to ge ...
spp.''), and hobblebush ('' Viburnum alnifolium'').


Successional relationships

''Betula papyrifera'' is a
pioneer species Pioneer species are hardy species that are the first to colonize barren environments or previously biodiverse steady-state ecosystems that have been disrupted, such as by wildfire. Pioneer flora Some lichens grow on rocks without soil, so ...
, meaning it is often one of the first trees to grow in an area after other trees are removed by some sort of disturbance. Typical disturbances colonized by paper birch are
wildfire A wildfire, forest fire, bushfire, wildland fire or rural fire is an unplanned, uncontrolled and unpredictable fire in an area of combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identi ...
,
avalanche An avalanche is a rapid flow of snow down a slope, such as a hill or mountain. Avalanches can be set off spontaneously, by such factors as increased precipitation or snowpack weakening, or by external means such as humans, animals, and ea ...
, or
windthrow In forestry, windthrow refers to trees uprooted by wind. Breakage of the tree bole (trunk) instead of uprooting is called windsnap. Blowdown refers to both windthrow and windsnap. Causes Windthrow is common in all forested parts of the w ...
areas where the wind has blown down all trees. When it grows in these pioneer, or early successional, woodlands, it often forms stands of trees where it is the only species. Paper birch is considered well adapted to fires because it recovers quickly by means of reseeding the area or regrowth from the burned tree. The lightweight seeds are easily carried by the wind to burned areas, where they quickly germinate and grow into new trees. Paper birch is adapted to ecosystems where fires occur every 50 to 150 years For example, it is frequently an early invader after fire in
black spruce ''Picea mariana'', the black spruce, is a North American species of spruce tree in the pine family. It is widespread across Canada, found in all 10 provinces and all 3 territories. It is the official tree of the province of Newfoundland and Lab ...
boreal forest Taiga (; rus, тайга́, p=tɐjˈɡa; relates to Mongolic and Turkic languages), generally referred to in North America as a boreal forest or snow forest, is a biome characterized by coniferous forests consisting mostly of pines, spruc ...
s. As paper birch is a pioneer species, finding it within mature or climax forests is rare because it will be overcome by trees that are more shade-tolerant as secondary succession progresses. For example, in Alaskan boreal forests, a paper birch stand 20 years after a fire may have , but after 60 to 90 years, the number of trees will decrease to as spruce replaces the birch. After approximately 75 years, the birch will start dying and by 125 years, most paper birch will have disappeared unless another fire burns the area. Paper birch trees themselves have varied reactions to wildfire. A group, or stand, of paper birch is not particularly flammable. The canopy often has a high moisture content and the understory is often lush green. As such, conifer crown fires often stop once they reach a stand of paper birch or become slower-moving ground fires. Since these stands are fire-resistant, they may become seed trees to reseed the area around them that was burned. However, in dry periods, paper birch is flammable and will burn rapidly. As the bark is flammable, it often will burn and may girdle the tree.


Wildlife

Birch bark is a winter staple food for
moose The moose (in North America) or elk (in Eurasia) (''Alces alces'') is a member of the New World deer subfamily and is the only species in the genus ''Alces''. It is the largest and heaviest extant species in the deer family. Most adult ma ...
. The nutritional quality is poor because of the large quantities of
lignin Lignin is a class of complex organic polymers that form key structural materials in the support tissues of most plants. Lignins are particularly important in the formation of cell walls, especially in wood and bark, because they lend rigidity a ...
, which make digestion difficult, but is important to wintering moose because of its sheer abundance. Moose prefer paper birch over
aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the '' Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (C ...
,
alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...
, and balsam poplar, but they prefer willow (''
Salix Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...
'' spp.) over birch and the other species listed. Although moose consume large amounts of paper birch in the winter, if they were to eat only paper birch, they may starve. Although
white-tailed deer The white-tailed deer (''Odocoileus virginianus''), also known as the whitetail or Virginia deer, is a medium-sized deer native to North America, Central America, and South America as far south as Peru and Bolivia. It has also been introduced t ...
consider birch a "secondary-choice food," it is an important dietary component. In Minnesota, white-tailed deer eat considerable amounts of paper birch leaves in the fall. Snowshoe hares browse paper birch seedlings, and grouse eat the buds. Porcupines and beavers feed on the inner bark. The seeds of paper birch are an important part of the diet of many birds and small mammals, including chickadees, redpolls,
vole Voles are small rodents that are relatives of lemmings and hamsters, but with a stouter body; a longer, hairy tail; a slightly rounder head; smaller eyes and ears; and differently formed molars (high-crowned with angular cusps instead of lo ...
s, and
ruffed grouse The ruffed grouse (''Bonasa umbellus'') is a medium-sized grouse occurring in forests from the Appalachian Mountains across Canada to Alaska. It is the most widely distributed game bird in North America. It is non-migratory. It is the only specie ...
. Yellow bellied sapsuckers drill holes in the bark of paper birch to get at the sap; this is one of their favorite trees for feeding on.


Conservation

The species is considered vulnerable in
Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th ...
, imperiled in
Illinois Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rock ...
,
Virginia Virginia, officially the Commonwealth of Virginia, is a state in the Mid-Atlantic and Southeastern regions of the United States, between the Atlantic Coast and the Appalachian Mountains. The geography and climate of the Commonwealth are ...
,
West Virginia West Virginia is a state in the Appalachian, Mid-Atlantic and Southeastern regions of the United States.The Census Bureau and the Association of American Geographers classify West Virginia as part of the Southern United States while the ...
, and
Wyoming Wyoming () is a state in the Mountain West subregion of the Western United States. It is bordered by Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho to the west, Utah to the southwest, and Colorado to t ...
, and
critically imperiled The NatureServe conservation status system, maintained and presented by NatureServe in cooperation with the Natural Heritage Network, was developed in the United States in the 1980s by The Nature Conservancy (TNC) as a means for ranking or categ ...
in Colorado and
Tennessee Tennessee ( , ), officially the State of Tennessee, is a landlocked U.S. state, state in the Southeastern United States, Southeastern region of the United States. Tennessee is the List of U.S. states and territories by area, 36th-largest by ...
.


Uses

''Betula papyrifera'' has a moderately heavy white wood. It makes excellent high-yielding firewood if seasoned properly. The dried wood has a density of and an energy density . Although paper birch does not have a very high overall economic value, it is used in furniture, flooring, popsicle sticks,
pulpwood Pulpwood is timber with the principal use of making wood pulp for paper production. Applications * Trees raised specifically for pulp production account for 15% of world pulp production, old growth forests 9% and second- and third- and more gene ...
(for paper),
plywood Plywood is a material manufactured from thin layers or "plies" of wood veneer that are glued together with adjacent layers having their wood grain rotated up to 90 degrees to one another. It is an engineered wood from the family of manufactured ...
, and oriented strand board. The wood can also be made into spears, bows, arrows, snowshoes, sleds, and other items. When used as pulp for paper, the stems and other nontrunk wood are lower in quantity and quality of fibers, and consequently the fibers have less mechanical strength; nonetheless, this wood is still suitable for use in paper. The sap is boiled down to produce birch syrup. The raw sap contains 0.9% carbohydrates (
glucose Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, u ...
,
fructose Fructose, or fruit sugar, is a ketonic simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galactose, that are absorb ...
,
sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refine ...
) as compared to 2 percent to 3 percent within
sugar maple ''Acer saccharum'', the sugar maple, is a species of flowering plant in the soapberry and lychee family Sapindaceae. It is native to the hardwood forests of eastern Canada and eastern United States. Sugar maple is best known for being the prim ...
sap. The sap flows later in the season than maples. Currently, only a few small-scale operations in Alaska and
Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...
produce birch syrup from this species.


Bark

Its bark is an excellent fire starter; it ignites at high temperatures even when wet. The bark has an energy density of and , the highest per unit weight of 24 species tested. Panels of bark can be fitted or sewn together to make cartons and boxes. (A birchbark box is called a '' wiigwaasi-makak'' in the Anishinaabe language.) The bark is also used to create a durable waterproof layer in the construction of sod-roofed houses. Many indigenous groups (i.e., Wabanaki peoples) use birchbark for making various items, such as canoes, containers, and wigwams. It is also used as a backing for porcupine quillwork and moosehair embroidery. Thin sheets can be employed as a medium for the art of birchbark biting.


Plantings

Paper birch is planted to reclaim old mines and other disturbed sites, often bare-root or small saplings are planted when this is the goal. Since paper birch is an adaptable pioneer species, it is a prime candidate for reforesting drastically disturbed areas. When used in landscape planting, it should not be planted near
black walnut ''Juglans nigra'', the eastern American black walnut, is a species of deciduous tree in the walnut family, Juglandaceae, native to North America. It grows mostly in riparian zones, from southern Ontario, west to southeast South Dakota, south to ...
, as the chemical
juglone Juglone, also called 5-hydroxy-1,4-naphthalenedione (IUPAC) is an organic compound with the molecular formula C10H6O3. In the food industry, juglone is also known as C.I. Natural Brown 7 and C.I. 75500. It is insoluble in benzene but soluble i ...
, exuded from the roots of black walnut, is very toxic to paper birch. Paper birch is frequently planted as an ornamental because of its graceful form and attractive bark. The bark changes to the white color at about 3 years of growth. Paper birch grows best in USDA zones 2–6, due to its intolerance of high temperatures. '' Betula nigra'', or river birch, is recommended for warm-climate areas warmer than zone 6, where paper birch is rarely successful. ''B. papyrifera'' is more resistant to the bronze birch borer than ''
Betula pendula ''Betula pendula'', commonly known as silver birch, warty birch, European white birch, or East Asian white birch, is a species of tree in the family Betulaceae, native to Europe and parts of Asia, though in southern Europe, it is only found ...
'', which is similarly planted as a landscape tree.


Pests

Birch skeletonizer is a small larva that feeds on the leaves and causes browning. Birch leafminer is a common pest that feeds from the inside of the leaf and causes the leaf to turn brown. The first generation appears in May but there will be several generations per year. Severe infestations may stress the tree and make it more vulnerable to the bronze birch borer. When a tree is stressed, bronze birch borers may kill the tree. The insect bores into the sapwood, beginning at the top of the tree and causing death of the tree crown. The insect has a D-shaped emergence hole where it chews out of the tree. Healthy trees are resistant to the borer, but when grown in sub-ideal conditions, the defense mechanisms of the tree may not function properly. Chemical controls exist.


In culture

It is the provincial tree of
Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...
and the state tree of
New Hampshire New Hampshire is a U.S. state, state in the New England region of the northeastern United States. It is bordered by Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec t ...
. People sometimes vandalize the bark of this tree by carving into it with a knife or by peeling off layers of the bark. Both forms of vandalism can cause scars on the tree.


References


External links


Flora of North America – Distribution Map: ''Betula papyrifera''
{{Authority control papyrifera Hardwood forest plants Trees of Subarctic America Trees of Western Canada Trees of Eastern Canada Trees of the Northwestern United States Trees of the North-Central United States Trees of the Northeastern United States Trees of continental subarctic climate Trees of humid continental climate